In 1907, Duncan MacDougall of Haverhill, Massachusetts decided to try and prove the existence of the soul.
All he needed was a set of scales, some people willing to die under his supervision, and some dogs.
(Thread, sources here: https://t.co/eAjnXjI4Rj)
The doctor, for reasons he didn't take time to note down, believed that the soul had physical mass and thus it should be possible to weigh it.
He had the imagination to believe that a piece of soul magically departs your body when you die, possibly to live in a heaven-like place for eternity, but thought it unrealistic that this couldn't be weighed like a bag of flour.
He decided the best way to prove his theory would be to weigh somebody at the precise moment they snuffed it, and then immediately after. The weight disparity would be the weight of the departed soul.
MacDougall looked for volunteers that would be up for the job of dying, and, shortly before that, having their last act on Earth be a fucking weigh-in.